Printed documents may be provided with machine-readable links. Such links may be optically readable by a computing device with an image capture device making the printed document interactive using such computing devices. The machine-readable inks may be encoded or associated with various types of information, which in turn may supplement or complement the content of the printed document. Examples of such links include one- or two-dimensional barcodes, digital watermarks, image fingerprints, and the like. Interaction with such machine-readable links allows any user to access information encoded within the respective machine-readable links.